This invention relates to traffic analyzers for local area networks, and in particular to traffic analyzers that record information regarding traffic patterns between stations on a transmission medium included in a local area network.
A local area network typically includes a number of stations, each having a respective address, interconnected by a transmission medium. For example, a suitable transmission medium may be a fiber optic cable, a twisted pair, or a radio link. Typically, each of the stations in the network includes means for sending message packets to selected other stations in the network via the transmission medium, as well as means for receiving message packets. Each message packet will generally include both the source address (identifying the sending station) and the destination address (identifying the intended receiving station), as well as the data being transmitted.
In the past, statistics regarding the patterns of traffic between individual pairs of stations have been collected by means of a traffic monitor that includes a computer programmed to monitor message packets on the transmission medium. To do this, each packet is examined and information is stored indicative of the number of packets sent between each active pair of stations.
There may be a great number of packets sent on a network, and certain networks include a large number of active pairs of stations communicating with one another. For these reasons, substantial computer time or hardware may be required to efficiently store traffic patterns between pairs of active stations. For example, if table entries indicative of the source address, destination address, and number of packets exchanged were simply stored in an unordered list, searching the list and inserting new entries into the table as appropriate could be very time consuming. If the method for searching the table were linear, on average half of the entries of the table would have to be searched for every packet received. A sorted table would allow for a binary search method, but then adding a new entry to the table for a new source and destination pair would be slow, requiring that a considerable amount of data in the table be moved for each newly active source-destination pair of stations.
It is one object of the present invention to provide an improved system for recording information regarding traffic patterns between stations on a transmission medium, which system does not require excessive memory or computer time to implement, yet which is highly efficient and effective in use, even with large networks where a large number of message packets are being monitored.